1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙钳形受体对卤素阴离子的识别机理

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)和HF(Hatree-Fock)方法, 从理论上探讨了1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙(DAPHZ)钳形受体对卤素阴离子的识别机理,结果发现DAPHZ受体以其钳形结构中的-N-H基团与卤素阴离子间形成双侧红移氢键进行识别. 经BSSE校正后DAPHZ•••F-, DAPHZ•••Cl-和DAPHZ•••Br-体系的分子识别相互作用能ΔECP分别为-327.5,-163.5和-148.3 kJmol-1, 说明钳形DAPHZ受体对F-具有最好的识别能力. 此外, 采用自然键轨道(NBO)计算, 相关H原子化学位移计算及分子中原子(AIM)等理论分析了识别体系中红移氢键的电子结构和性质, 结果表明APHZ受体对卤素阴离子的识别能力的相对顺序为DAPHZ•••F- >> DAPHZ•••Cl- ≈ DAPHZ•••Br-.     

间-苯二氧乙酰-(N-苯甲酰基)肼钳形受体对卤素阴离子的识别机理

采用密度泛函B3LYP（Bccke.thrcc-paramctcr,Lee-Yang-Parr）方法探讨了间-苯二氧乙酰-（N-苯甲酰基）肼（DAPHZ）受体对卤素阴离子的识别机理,结果发现DAPHZ钳形受体C构型以其钳形结构中的N-H键与卤素阴离子间形成多齿红移氢键进行识别,其中C…X^-（X=F^-,Cl^-和Br^-）体系中主客体间以双齿氢键识别结合,而在C…I^-体系中主客体间以三齿氢键识别结合,说明钳形受体C对I^-在空间几何上具有最好的匹配性.经BSSE校正后的C…F^-,C…Cl^-,C…Br^-和C…I^-体系分子识别相互作用能△E_CP分别为-314.0,-200.1,-183.3和-136.3 kJmol^-1,说明钳形受体C对F^-在热力学上具有最好的识别能力.此外,采用自然键轨道（NBO）)分析及分子中原子（AIM）等理论分析了C…X^-（X=F^-,Cl^-,Br^-和I^-）识别体系中红移氢键的电子结构和性质.     

同时基于氢键和卤键的尿素含碘衍生物对卤素阴离子的识别机理

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)量子化学理论方法探讨了同时基于氢键和卤键者两种弱相互作用的尿素无氟含碘衍生物对卤素阴离子（F-,Cl-,Br-和I-）的识别机理, 结果发现尿素衍生物受体分子A以其结构中的两个N-H键和两个C-I与卤素阴离子间形成四齿弱键进行识别. 其中包括2个N-H…X-红移氢键和2个C-I…X-蓝移卤键弱相互作用. 另外, 经BSSE校正后的A…F-, A…Cl-, A…Br-和A…I-分子识别体系中相互作用能ΔECP分别为-48.90, -121.78, -311.42和-96.55 kJ/mol, 从结合强度上来看, 受体A对Br-和Cl-具有较好的识别能力, 而对F-的识别能力相对较弱. 此外, 采用自然键轨道(NBO)理论分析了C…X-（X= F-,Cl-,Br-和I-）识别体系中红移氢键和蓝移卤键的电子行为与性质.     

同时基于氢键和卤键的尿素含碘衍生物对卤素阴离子的识别机理北大核心CSCD

采用密度泛函B3LYP(Becke,three-parameter,Lee-Yang-Parr)量子化学理论方法探讨了同时基于氢键和卤键者两种弱相互作用的尿素无氟含碘衍生物对卤素阴离子(F-,Cl-,Br-和I-)的识别机理,结果发现尿素衍生物受体分子A以其结构中的两个N-H键和两个C-I与卤素阴离子间形成四齿弱键进行识别.其中包括2个N-H…X-红移氢键和2个C-I…X-蓝移卤键弱相互作用.另外,经BSSE校正后的A…F-,A…Cl-,A…Br-和A…I-分子识别体系中相互作用能ΔECP分别为-48.90,-121.78,-311.42和-96.55kJ/mol,从结合强度上来看,受体A对Br-和Cl-具有较好的识别能力,而对F-的识别能力相对较弱.此外,采用自然键轨道(NBO)理论分析了C…X-(X=F-,Cl-,Br-和I-)识别体系中红移氢键和蓝移卤键的电子行为与性质.     

N-芳基-N′-(4-乙氧基苯甲酰基)硫脲衍生物阴离子识别性能的光谱研究

利用紫外-可见吸收光谱及1H NMR考察了两种N-芳基-N′-(4-乙氧基苯甲酰基)硫脲作为受体分子与F-,Cl-,Br-,I-,CH₃COO-,H₂PO-₄,HSO-₄,NO-₃等阴离子的作用。结果表明,客体阴离子F-,CH₃COO-,H₂PO-₄可以与该类受体分子形成氢键配合物,溶液颜色由无色转变为黄色,而加入其他阴离子则无变化。测定了主客体配合物的稳定常数和化学配位比,对苯环上不同取代基的受体分子与不同阴离子客体的识别作用以及同一受体对不同阴离子的识别作用进行了比较,其识别性能呈现规律性变化, 提出了可能的配合物的结合模式。     

5-(二甲基氨基)-N-(4-(2-(2-羟基亚苄基)甲酰肼基)苯基)萘-1-磺酰胺的合成及对锌离子识别的光谱性能研究

合成了含有丹磺酰胺荧光团的新型Zn2+荧光探针DH1(5-(二甲基氨基)-N-(4-(2-(2-羟基亚苄基)甲酰肼基)苯基)萘-1-磺酰胺),利用光谱法研究它对锌离子的识别作用。光谱滴定和ESI-MS谱分析表明DH1与Zn2+以1∶1的化学计量数配位。在CH3CN/H2O(φ,9∶1)体系中,DH1与Zn2+结合后荧光显著增强,量子产率高达0.53,荧光检测限达到1.0×10-7 mol.L-1,而其他常见金属离子,如K+,Li+,Na+,Mg2+,Ca2+,Cr3+,Mn2+,Ni 2+,Pb2+,Cu2+,Cd2+,Co2+,Fe2+及Hg2+不引起荧光光谱变化。结果表明,DH1对锌离子识别具有较高的选择性和灵敏度。     

3-[5-(α-萘)-2H-四唑-2-甲撐-4-苯基-1,2,4-三唑啉-5-硫酮13C-NMR的研究

本文研究了5-(α-萘)-四唑(Ⅱ),5-(α-萘)-2H-四唑-2-乙酸甲酯(Ⅲ),5-(α-萘)-2H-四唑-2-乙酰肼(Ⅳ),1-[5-(α-萘)-2H-四唑-2-乙酰]-4-苯基氨基硫脲(V)以及3-[5-(α-萘)-2H-四唑-2-甲撐]-4-苯基-1,2,4-三唑啉-5-硫酮(Ⅵ)的¹³C核磁共振谱和各种¹³C-NMR化学位移。根据化学位移理论、讯号强度以及同模型化合物化学位移的比较,辨认其归属。     

光谱法考察对称四甲基六元瓜环与二氯化-二(2-苯并咪唑)丁烷的分子识别

以对称四甲基六元瓜环为主体,二氯化-二(2,2’-苯并咪唑)丁烷为客体,采用荧光光谱法和紫外吸收光谱法研究了主客体的相互作用。实验结果表明,主体对客体具有较强的包结识别能力,主客体之间可形成1∶1及2∶1的包结配合物,紫外吸收光谱法测得配合物的包结常数为K_(1∶1)=4.79±0.01×104 L·mol-1, K_(2∶1)=8.51±0.01×1010 L2·mol-2; 荧光光谱法测得配合物的包结常数为K_(1∶1)=7.02±0.01×104 L·mol-1, K_(2∶1)=2.88±0.01×1010 L2·mol-2,两种方法结果一致。     

Dynamical properties and the proton transfer mechanism in the wetting water layer on Pt(1 1 1)

We have investigated the structural properties and the dynamics in the ()R16.1° (RT39) wetting layer on Pt(1 1 1) found in recent experiments, by ab initio molecular dynamics simulations. The RT39 bilayer is found to consist of 20% water molecules in the first flat layer, and 66% in the second layer, and a small fraction extending further away. Two-dimensional pair correlation functions are obtained, and calculated vibration spectra are in agreement with experiment. A small fraction of water in this RT39 bilayer dissociates due to both the lateral compression and the substrate effect. Most interestingly, surface mediated proton transfer mechanism in water layers at surface, which differs from the counterparts in bulk water, is discovered.     

The effect of benzo‐annelation on intermolecular hydrogen bond and proton transfer of 2‐methyl‐3‐hydroxy‐4(1H)‐quinolone in methanol: A TD‐DFT study

Excited‐state intermolecular or intramolecular proton transfer (ESIPT) reaction has important potential applications in biological probes. In this paper, the effect of benzo‐annelation on intermolecular hydrogen bond and proton transfer reaction of the 2‐methyl‐3‐hydroxy‐4(1H)‐quinolone (MQ) dye in methanol solvent is investigated by the density functional theory and time‐dependent density functional theory approaches. Both the primary structure parameters and infrared vibrational spectra analysis of MQ and its benzo‐analogue 2‐methyl‐3‐hydroxy‐4(1H)‐benzo‐quinolone (MBQ) show that the intermolecular hydrogen bond O₁―H₂?O₃ significantly strengthens in the excited state, whereas another intermolecular hydrogen bond O₃―H₄?O₅ weakens slightly. Simulated electron absorption and fluorescence spectra are agreement with the experimental data. The noncovalent interaction analysis displays that the intermolecular hydrogen bonds of MQ are obviously stronger than that of MBQ. Additionally, the energy profile analysis via the proton transfer reaction pathway illustrates that the ESIPT reaction of MBQ is relatively harder than that of MQ. Therefore, the effect of benzo‐annelation of the MQ dye weakens the intermolecular hydrogen bond and relatively inhibits the proton transfer reaction.     

The equilibrium and kinetics of intermolecular hydrogen bonding in nitroarene anion radical–alcohol system: 1,3‐dinitro‐benzene anion radical – R–OH (R═CH3–, C2H5–, (CH3)2 CH–)

To explore the possibility of hydrogen bonding of a stable anion radical with DNA – component sugar, hormones, steroid, and so on (through hydroxyl group), as a first step, the possibility of hydrogen bonding of 1,3‐dinitrobenzene anion radical (1,3‐DNB^??) with aliphatic alcohols was studied. It was found that 1,3‐DNB^?? anion radical undergoes hydrogen bonding with alcohols: methanol, ethanol, and 2‐proponal. The hydrogen‐bonding equilibrium constant K_eq and the (hydrogen‐bonding) rate constants k₂ were evaluated through the use of linear scan and cyclic voltammetry theory and techniques. The K_eq was found to be in the range of 1.4–6.0 m ^?1, whereas the rate constants k₂ were found to be in the range of 1.5–3.6 m ^?1 s^?1, depending upon the hydrogen‐bonding agent and the equation used for the calculation of the rate constants. The hydrogen‐bonding number n was found to be around 0.5 or 1.0. The implication of this study in, for example, the replication of DNA, the prevention of the formation of super oxide, and so on is discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Theoretical studies on the molecular dependence of the bond dissociation after the core excitations. CH3OCO(CH2)nCN, n=0, 1, 2

Approximate theoretical normal and resonant Auger spectra for a series of methyl cyanoesters were calculated. To study the reported molecular dependence of the fragmentation patterns after the core excitations, a new measure, bond dissociation factor, was introduced. The site-selectivity and the state-specificity for a series of methyl cyanoesters are qualitatively explained.     

PdY合金及其一氢化物分子结构及热力学函数的研究

本文利用B3LYP的密度泛函方法对PdY、 PdYH的分子结构进行了优化,得到PdY最稳定的电子态为2∑,RPdY=0.2418 nm,ωe=249.66cm-1,De=2.75eV.PdYH最稳定构型为Cs,1A'态,RPdY=0.243 0 nm,RYH=0.197 4nm,∠PdYH=116.54°,谐振频率v1(a')=1 450.83cm-1,v2(a')=351.21cm-1,v3(a')=243.71cm-1,离解能De(PdYH)为5.64 eV.并以气态分子总能量中的振动能Ev代替分子处于固态时的振动能,以电子运动和振动运动熵SEv代替分子处于固态的熵的近似方法计算了PdY与氢及其同位素反应的△Hθ、△Sθ、△Gθ及氢化反应平衡压力,得出PdYH(S)的生成焓为60.32kJ·mol-1.     

Substrate induced enhancement of atomic layer growth on Al(1 1 1): The effect of the mass anisotropy

The evolution of the thin-film morphology is studied by molecular dynamics simulations and we find a strong tendency of adatom island growth on the (1 1 1) surface of a thin Al overlayer placed on a heavy substrate (Pt(1 1 1)) when the system is subjected to low-energy Xe⁺ irradiation. The large adatom yield of 10²−10³ is found for 5-10 keV rare gas ion impacts. We also find that the mass effect due to the small atomic mass ratio (large mass anisotropy) in the bilayer has a direct effect on the atomic layer growth on the surface. A mass anisotropy induced scattering of the light overlayer atoms from the heavy substrate contributes to the enhancement of adatom production. It has been found that the volume increase (density decrease) of the amorphous intermixed phase keeps the adatoms on the surface. The competition between cratering and atomic layer growth can also be seen: three events out of 10 leads to cratering (erosion) morphology at 6 keV ion energy. The substrate induced enhancement of atomic layer growth might be a promising tool for making arrays of nanodots as nanotemplates for nanofabrication.